Traffic lights control the timing of traffic flows in the various directions. When the traffic light is green for a certain traffic flow direction, i.e., left turn for south bound traffic, vehicles in other directions are stopped. The length of that green light, known as green split, determines how long a queue traffics in each of the stopped direction will accumulate. Therefore, the phases and lengths of the green lights need to be controlled according to the traffic conditions in the various directions.
Existing traffic light controls are typically performed at individual traffic lights by their respective controllers. A traffic light is thus not coordinated with nearby traffic lights in order to control traffic flows in a large region. Further, existing traffic light controls rely on data acquired by fixed sensors (e.g., loop detectors, geomagnetic detectors, or video sensors that placed in strategic locations). However, the ability of fixed sensors to provide sufficient traffic information is limited due to its immobility. For example, insufficiency of detector coverage (e.g., in small cities or rural area where inadequate detectors are established) and damaged or malfunctioning detectors (e.g., due to deficient manpower for conducting routinely check) may reduce the quality and quantity of the data provided by fixed sensors. As a result, fixed sensors cannot obtain reliable data on continuous vehicle speeds, queue lengths, etc. Data acquisition by fixed sensor is also not cost-effective due to the infrastructure that needs to be installed, labor needed for maintaining and repairing the equipment, etc.
In addition, existing traffic light controls also rely heavily on human interventions. For example, traffic condition detection and reporting are performed by policemen or traffic patrols. Recording and downloading of traffic control schemes are performed by traffic engineers. Infrastructure maintained (such as fixed sensors) need to be done by experienced maintenance crews. The manual tasks performed as part of the existing traffic controls make the controls inevitably expensive.
Embodiments of the disclosure address the above problems by improved methods and systems for adaptive traffic control using vehicle trajectory data.